磷石膏生产纸面石膏板的预处理研究

Research on Pretreatment of Phosphogypsum for Gypsum Plasterboard Production

采用湿法磷酸生产中副产的磷石膏(二水硫酸钙)生产纸面石膏板时,磷石膏中的水溶性磷和氟会影响纸面石膏板的抗折强度,以及生产过程中的初凝、终凝时间;磷石膏的酸度会影响二水硫酸钙的结晶状态。试验表明:加水调浆后的磷石膏质量分数控制为60%,搅拌30 min后过滤,可除去47.62%(质量分数,下同)的水溶性磷和61.29%的氟;在加水调浆后的磷石膏中加入0.20%的生石灰,可以改善磷石膏的酸碱度,提高纸面石膏板的抗折强度。对磷石膏进行预处理,可以提高纸面石膏板的抗折强度,缩短生产过程中的初凝、终凝时间。

When the phosphogypsum(calcium sulfate dihydrate)by-product of wet process phosphoric acid production is used to produce gypsum plasterboard,the water-soluble phosphorus and fluorine in the phosphogypsum affect the flexural strength of the gypsum plasterboard,as well as the time of the initial and final coagulation in the production process.The acidity of the phosphogypsum affects the state of crystallization of the calcium sulfate dihydrate.Test results show that the mass fraction of the phosphogypsum after adding water to adjust the slurry is 60%,stirring for 30 min and then filtering,can remove 47.62%(mass fraction,the same below)of the water-soluble phosphorus and 61.29%of the fluorine.Adding 0.20%of quicklime to phosphogypsum after adding water to adjust the slurry,the acidity can be improved,and therefore improve the flexural strength of the gypsum plasterboard.Pretreatment of phosphogypsum can improve the flexural strength of gypsum plasterboard and shorten the initial and final setting time in the production process.